Marine Weather and Tide Forecast for Onset, MA

NEAR TERM /THROUGH TODAY/
Key Messages:

* Dry and mild today with sea-breezes developing

High pressure moves offshore today. Light N to NW winds gradually become Light S to SE winds by late morning. Dry weather expected through most of today. Near normal high temperatures along both immediate coasts, with above normal highs across the interior. Increasing clouds this afternoon. Low risk for very late day spotty showers across far NW Massachusetts.

SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/
Key Messages:

* Scattered showers developing tonight then moving offshore Tuesday * Well above normal high temperatures expected Tuesday

High pressure over the North Atlantic continues to move farther offshore tonight. A low pressure moving into the Great Lakes should first push a warm front across our region, which will provide the first chance for showers. While there is some elevated instability, am thinking the forcing is too weak to support thunderstorms past sunset. These showers could linger across the Cape and islands after daybreak Tuesday, while drier weather is anticipated elsewhere.

This will be followed by the weakening cold front of this system. Thus, expecting southern New England to remain in more of a warm sector environment Tuesday. Once the sunshine breaks out, there should be a rather significant warm up, at least away from the Cape and islands. Still contending with water temperatures in the mid 40s there.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
Key Messages:

* Mainly dry Wednesday and Thursday with temperatures slightly above normal.

* Pattern becomes more unsettled Friday through the weekend with periodic chances for precipitation.

Tuesday Night through Weekend:

A cold front moves through Tuesday night into early Wednesday morning. Wednesday trends slightly cooler than Tuesday, although still warmer than normal overall. Highs range in the 50s for the Cape/Island and 60s for the interior. Light NW winds expected under broad high pressure with localized sea breezes in the afternoon for the coastal areas.

A similar pattern stays in place through the end of the week with zonal flow and 850mb temperature anomalies signaling at slightly above normal temperatures. Ensemble guidance shows a transition to a more unsettled pattern Friday into the weekend.
Heights fall across the region ahead of an upper level trough moving over the Great Lakes. A weaker leading shortwave moves through Friday evening with the main trough moving through by the end of the weekend. This will bring a few rounds of precipitation. Still need to iron out the details with the timing/chances of the first wave of showers on Friday. A more consistent round of rain moves in overnight through Saturday.
Temperatures range around normal. Conditions gradually dry out Sunday.

AVIATION /06Z MONDAY THROUGH FRIDAY/
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Today...High Confidence.

VFR. Light to calm winds early. Sea-breezes developing along the east coast of MA 13-15z. Otherwise, wind becoming S 10-15 kt this afternoon.

Tonight...High confidence in trends. Moderate confidence in timing.

VFR this evening, lowering to MVFR-IFR from W to E after 05z.
Scattered showers developing.

Tuesday...High confidence in trends. Moderate confidence in timing.

MVFR/IFR to start, then transitioning to VFR by late morning across most of the region. VFR more likely to develop in the early afternoon for the Cape and islands. S to SW winds 10-15 kt.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night: VFR. Breezy.

Wednesday through Thursday Night: VFR.

Friday: VFR. Slight chance SHRA.

MARINE
Forecaster Confidence Levels:

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

Through Tuesday...High Confidence.

Rather tranquil boating conditions across the waters today and tonight. Increasing S to SW winds Tuesday ahead of a dissipating cold front approaching the waters. This could lead to marginally rough seas across portions of the southern outer coastal waters.
Risk for some showers with reduced visibility after midnight.
These showers are expected to move east of the waters by Tuesday afternoon, but could leave some patch fog in their wake.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft.

Wednesday through Thursday Night: Winds less than 25 kt.

Friday: Winds less than 25 kt. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...None.